Sulfur-products from compositions of unsaturated esters, usable as additives for lubricants

ABSTRACT

Additives for lubricants are disclosed which result from the sulfur-treatment of compositions comprising from 10 to 100 percent by moles of an unsaturated complex ester of the formula:   and from 0 to 90 % by mole of an unsaturated ester of the formula:   in which R1 is a monovalent aliphatic remainder of a monocarboxylic acid having a monoethylenic aliphatic chain, R2 is a divalent aliphatic remainder of a diol or a divalent group of the formula -R-O-m R-, R being a divalent saturated aliphatic radical, m an integer of small value, and R3 is a divalent aliphatic remainder of dicarboxylic acid.

United States Patent Bourdoncle et al.

[ SULFUR-PRODUCTS FROM COMPOSITIONS OF UNSATURATED ESTERS, USABLE AS ADDITIVES FOR LUBRICANTS [75] Inventors: Bernard Bourdoncle,

Rueil-Malmaison; Bernard Sillion, Grenoble; Jean Ayel, Neauphle-le-Chateau, all of France [73] Assignee: Institut Francais du Petrole des Carburanta et Lubrifiants, Rueil-Malmaison, France 22 Filed: Mar. 27, 1973 21 Appl. No.: 345,285

[30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 914,661 6/1960 United Kingdom 260/l25 Primary Examiner-Lewis Gotts Assistant Examiner-D. R. Phillips Attorney, Agent, or Firm-Millen, Raptes & White [5 7] ABSTRACT Additives for lubricants are disclosed which result from the sulfur-treatment of compositions comprising from 10 to 100 percent by moles of an unsaturated complex ester of the formula:

and from O to 90 by mole of an unsaturated ester of the formula:

in which R is a monovalent aliphatic remainder of a monocarboxylic acid having a monoethylenic aliphatic chain, R is a divalent aliphatic remainder of a die] or a divalent group of the formula +ROm+R-, R being a divalent saturated aliphatic radical, m an integer of small value, and R is a divalent aliphatic remainder of dicarboxylic acid.

19 Claims, No Drawings SULFUR-PRODUCTS FROM COMPOSITIONS OF UNSATURATED ESTERS, USABLE AS ADDITIVES FOR LUBRICANTS This invention concerns the field of the additives for lubricants. More particularly, it concerns sulfurized products from compositions of unsaturated esters, usable as additives for lubricating compositions.

The evolution of modern mechanics tends towards the use of machines having higher and higher performances and, consequently, the use of more and more loaded mechanisms, whose lubrication is difiicult to achieve, particularly with regard to the maintenance of the oil film, due to the existence of a limit running condition for lubrication. This is specially the case not only in the case of mechanically loaded gears, but also in the case of metal working, and more particularly, in metal cutting. When the maintenance of the oil film is no longer ensured, seizing occurs whereby the machine or the tool may be destroyed.

In order to avoid the above-mentioned drawbacks, the best solution consists in improving the lubricity of the oil, i.e., the resistance of the oil film, particularly by addition of a small amount of sulfurized spermaceti oil. However, in view of a new regulation which forbids cachalot fishing, the natural spermaceti oil will no longer be available.

It is, accordingly, an object of the present invention to provide compositions of unsaturated esters from which it is possible to manufacture additives for lubricants which are capable of imparting to the lubricating oils, as well the mineral as the synthetic oils, lubricity, anti-wear and extreme-pressure properties which, in most cases, are higher than those obtained with a sulfurized spermaceti oil.

This is a further object of the invention to provide an advantageous process for manufacturing additives for lubricants, making use as starting compounds of products which are now readily available, inexpensive and are unlikely ever to be in short supply.

The compositions of unsaturated esters used as starting compounds in this invention comprise fi'om 10 to I by mole of at least one unsaturated complex ester of the general formula:

0 o 0 H II and from 0 to 90 by mole of at least one unsaturated ester of the general formula:

iunsaturated mixtures of monocarboxylic acids containing acids with a monoethylenic aliphatic chain as well as acids with a saturated aliphatic chain and/or acids whose aliphatic chain has more than one ethylenic unsaturation (for example 2 and 3). Radicals R may, for example, contain from to 23 carbon atoms and,

more particularly in the second case, from 15 to 17 carbon atoms.

The radicals R which are identical to or different from each other, are saturated or unsaturated, linear or branched divalent aliphatic hydrocarbon remainders of diols or divalent groups of the formula 4 R O ,,,R in which R is a saturated divalent aliphatic hydrocarbon radical containing 2 or 3 carbon atoms and m is a low integer, for example 1 or 2; the radicals R contain for example 2 to 6 carbon atoms.

R; is a saturated or unsaturated, linear or branched divalent aliphatic hydrocarbon remainder of a dicarboxylic acid. It contains for example, from 1 to 20 carbon atoms.

The composition of unsaturated esters used according to the invention, are prepared by total esterification of at least one diol of the formula HO R OH by a mixture of at least one monocarboxylic acid of the formula and at least one dicarboxylic acid of the formula in which the radicals R R and R are as defined herein above, the proportion of dicarboxylic acid being preferably from 0.05 to 0.5 mole per mole of monocarboxylic acid and the amount of the mixture of said carboxylic acids being such that all the hydroxy functions of the one or more diols are esterified.

As examples of diols, there can be mentioned ethylene glycol, propylene glycol, butenediol, neopentylglycol, hexanediol, diethyleneglycol, triethyleneglycol, dipropyleneglycol and tripropyleneglycol. As examples of unsaturated monocarboxylic acids, there can be mentioned fatty acids such as undecenoic acid and oleic acid.

As examples of unsaturated mixtures of monocarboxylic acids, there can be mentioned certain mixtures of fatty acids such as soja oil, colza oil or Tall Oil, which are particularly advantageous since they are easily available.

In the following table there are mentioned by way of illustration the approximate composition of the fatty acids of soja and the fatty acids of Tall Oil:

(linolenic isomers) As examples of dicarboxylic acids, there can be mentioned maleic acid, fumaric acid, succinic acid, adipic acid, azelaic acid, trimethyl adipic acid, sebacic acid, dodecanedioic acid, and the alkenylsuccinic acids such as tetrapropenylsuccinic acid.

The complete esterification of the diol by means of the mixture of monoand di-carboxylic acids, may be carried out according to any convenient method. In particular, the process may include a reflux of a solvent such for example as benzene, toluene or xylene with an azeotropic removal of the formed water and the reaction may be catalyzed with from 0.1 to 2 by weight of an acid such for example as paratoluene sulfonic acid. After evaporation of the solvent, the esterification product may be purified for example by treatment with active earth.

According to other processes for manufacturing the compositions of unsaturated esters used according to the invention, it is possible to make use, instead of the mono and dicarboxylic acids themselves, of certain of their functional derivatives such as chlorides, anhydrides or lower alkyl esters.

The compositions of unsaturated esters used in this invention, have, according to the nature and the proportions of their constituents, a degree of unsaturation which may vary from about 0.20 to about 0.60 ethylenic bonds for 100 grams. For example, in the case of the use of a monocarboxylic acid with one ethylenic unsaturation, the degree of unsaturation of the composition may be more particularly from about 0.24 to 0.42 ethylenic bonds for 100 grams and, in the case of the use of a mixture of monocarboxylic acids of the type of fatty acids of Tall Oil, the unsaturation degree of the composition is more particularly from about 0.35 to 0.61.

The invention especially relates to sulfur-products from the compositions of unsaturated esters defined hereinabove and more particularly the products whose sulfur content is from 6 to 12 by weight. When the unsaturation degree of the composition makes it possible, the sulfur content may be higher than 12 and for example as high as 15 by weight.

The sulfurization of the compositions of unsaturated esters may be carried out according to any known method. However, best results are obtained by using the following preferred method:

To 100 parts by weight of a composition of unsaturated esters as defined hereinabove, from 7 to 15 parts by weight of elemental sulfur, and from 0.5 to 2 parts by weight of zinc oxide are added.

The reaction mixture, under vigorous stirring and under an inert atmosphere with respect to the reactants, is brought to a temperature of from 145 to 175C, during a period of, for example, from to hours. After this first treatment, the temperature is increased to l 80-200C, during a period of, for example, from 2 to 4 hours. During said second stage, a minor portion of the reacted sulfur, close to 10 by weight of the total sulfur, is removed in the form of hydrogen sulfide.

The product obtained, after filtration, is the sulfurized composition according to the invention.

It is noticeable that the presence of zinc oxide in the reaction medium, although it is not necessary, has however the advantage of orienting the fixation of the su1- fur in such a way that the resulting product has improved anti-wear properties and a very reduced corrosivity with regard to the usual metals and, particularly,

copper.

Furthermore, it may be advantageous to carry out the sulfurizing reaction, conducted for example according to the above described method, on a composition of unsaturated esters, diluted in an amount of, for example, from 10 to 40 by weight of a substrate such as a light mineral oil corresponding for example to grade SAE 10 W or 5 W or a synthetic oil such for example as, isodecyl adipate.

Among the synthetic oils which may be advantageously used, there can be mentioned, by way of example, the esters obtained by total esterification of an aliphatic alcohol having from 1 to 13 carbon atoms (such for example as, n.hexanol, n,heptanol, 2-ethyl hexanol, isononanol or isodecanol) by means of one or more monocarboxylic acids having from 11 to 23 carbon atoms such as oleic acid (9-octadecenoic) or linoleic acid (9,12-octadecadienoic) or one or more dicarboxylic acids having from 4 to 12 carbon atoms such as maleic, fumaric, succinic, adipic and dodecanedioic acids. As particularly advantageous, there can be mentioned the esters obtained by total esterification of one of the above-mentioned aliphatic alcohols by means of fatty acids of Tall Oil such as already described, and particularly, the esters of 2-ethyl-hexanol and isononanol.

Finally, when it is desired to enhance specifically the extreme-pressure properties of the sulfurized product, it is convenient to react the same for a period of, for example, 2 to 8 hours and at a temperature of 90 to 120C, with phosphorous sesquisulfide (P 8 in an amount of, for example, 0.2 to 0.6 by weight.

The sulfurized products according to the invention are used as additives for lubricants, as well for mineral as for synthetic oils. Generally, they are added to the lubricant bases in amounts of from 0.5 to 10 by weight and preferably from 1 to 5 by weight of the lubricant bases. They confer to said bases anti-wear and extreme-pressure properties which are substantially improved, without noticeably modifying the pour point.

The sulfurized products which are theoretically the most interesting for said uses are those which result from the sulfurization of unsaturated ester compositions as formed exclusively from complex esters of formula (1) (100 However in most cases, one has to make use of compositions which also contain a certain amount of unsaturated ester of general formula (2), in order to obtain additives which are miscible in the oils to a sufi'icient extent and which confer to the same satisfactory anti-wear and extreme-pressure properties as well as a good lubricity.

The following examples illustrate the invention, but

' are by no way to be considered aslimitative of the scope thereof.

In each of examples 7 to l l, the mixture of monocarboxylic acids with an aliphatic chain consists of a mix- I ture of fatty acids obtained by distillation of Tall Oil and have the following characteristics and composition:

(hexadecanoic) EXAMPLE 1 Into a 2-liter flask, 565 g (2 moles) of oleic acid, 80.7 g (1.3 mole) of ethyleneglycol, 35.4 g (0.3 mole) of succinic acid, 5 g of paratoluene sulfonic acid and 400ml of benzene are introduced. The mixture is heated to slight reflux. The formed water is continuously recovered by decantation in a Dean and Stark system. During the esterification, the prevailing temperature is 132134C. After 8 hours, 46.8g of water is recovered and the heating is discontinued. After washing with water and evaporation of benzene, 634 g of a composition of unsaturated ester is obtained.

Into a reaction vessel of a 500 ml capacity, equipped with a stirring system, there are placed 200 g of said composition of unsaturated complex ester, 26 g of sulfur and 2g of zinc oxide. The mixture is heated and stirred under a nitrogen atmosphere during 7 hours at 160C, then during 3 hours at 185C. After filtration, there is obtained 223g of additive I, having the following characteristics:

Viscosity at 989C 103 cSt Pour point 11C Sulfur content 10.6 by weight EXAMPLE 2 Into a 2-liter flask, there are introduced 565 g (2 moles) of oleic acid, 116.7 g (1.1 mole) of diethyleneglycol, l 1.6 g (0.1 mole) of fumaric acid, 5 g of paratoluene sulfonic acid, 2 g of phosphoric acid and 400 ml of toluene.

After reflux for 9 hours, 39.6 g of water is recovered. After washing with water and evaporation of toluene, 653 g of a composition of unsaturated ester is obtained. Thereafter, 200 g of the resultant composition of unsaturated ester are stirred with 23 g of sulfur and 2 g of zinc oxide under a nitrogen atmosphere for 7 hours at 160C and then for 3 hours at 185C.

After filtration, there is obtained 218g of additive 11, having the following characteristics:

Viscosity at 98.9C 92 cSt Pour point --13C Sulfur content 8.9 by weight EXAMPLE 3 Into a 2-liter flask, there are introduced 565 g (2 moles) of oleic acid, 166.6 g (1.6 mole) of neopentylglycol, 87.7 g (0.6 mole) of adipic acid, 6 g of paratoluene sulfonic acid and 400 ml of benzene. After reflux for 9 hours, 57.5 g of water is recovered. The contents of the flask are then washed with water, the toluene is evaporated, and 819 g of a composition of unsaturated ester, is obtained. Thereafter 200 g of said composition of unsaturated ester, is stirred with 18 g of sulfur and 2 g of zinc oxide are stirred under nitrogen atmosphere for 7 hours at 160C and then for 3 hours at 185C.

After filtration, there is obtained 215g of additive 111 having the following characteristics:

Viscosity at 989C 87 cSt Pour point l7C Sulfur content 7.6

EXAMPLE 4 According to the same procedure as in example 1, the reaction is conducted with 565 g (2 moles) of oleic acid, 127.5 g (1.2 mole) of diethylene glycol, 29.2 g (0.2 mole) of adipic acid and 6 g of paratoluene sulfonic acid in 400 ml of toluene. After reflux for 8 hours, 43 g of water are recovered. The mixture is then washed with water, the toluene is evaporated, and 678 g of a composition of unsaturated ester is obtained. Into reaction vessel 500-ml reaction vessel, there are introduced 200 g of this composition of unsaturated ester, 28 g of sulfur and 2g of zinc oxide. The mixture is stirred under a nitrogen atmosphere for 7 hours at C and then for 3 hours at C. After filtration, there is obtained 225g of additive IV having the following characteristics:

Viscosity at 989C 102 cSt Pour point 10C Sulfur content 11.5

EXAMPLE 5 According to the same procedure as in example 1, the reaction is conducted with 368.1 g (2 moles) of undecenoic acid, 135.5 g (1.3 mole) of neopentyl-glycol, 43.8 g (0.3 mole) of adipic acid and 5 g of paratoluene sulfonic acid in 300 ml of toluene.

After reflux for 8 hours, 45.4 g of water is recovered. The content of the flask are then washed with water and the toluene evaporated. There is obtained 500 g of a composition of unsaturated ester.

Into a 500-ml reactor, there are introduced, 200g of said composition of unsaturated ester, 21 g of sulfur and 2g of zinc oxide. The mixture is stirred under nitrogen atmosphere for 7 hours at 160C and then for 3 hours at 185C. After filtration, there is obtained 225 g of additive V having the following characteristics:

Viscosity at 989C 78 cSt Pour point l2C Sulfur content 8.7

EXANIPLE 6 According to the same procedure as in example 1, the reaction is conducted with 565 g (2 moles) of oleic acid, 124.2 g (2 moles) of ethylene glycol, 146 g (1 mole) of adipic acid and 5 g of paratoluene sulfonic acid in 300 ml of benzene. After reflux for 8 hours, 72 g of water is recovered. The contents of the flask is then washed with water and the benzene evaporated. There is obtained 761 g of a composition of unsaturated ester. Thereafter, 200 g of this composition of unsaturated ester, are stirred with 15 g of sulfur and 2 g of zinc oxide under a nitrogen atmosphere for 7 hours at 160C and then for 3 hours at 185C.

After filtration, there is obtained 203 g of additive VI having the following characteristics:

Into a 2-liter flask, there are placed 570 g (2 acid equivalents) of a mixture of fatty acids of Tall Oil, I

114.5 g (1.1 mole) of neopentylglycol, 14.6 g (0.1 mole) of adipic acid, 5 g of paratoluene sulfonic acid and 400 ml of benzene. The mixture is heated to slight reflux. The formed water is recovered continuously by decantation in a Dean and Stark system. During the esterification, the prevailing temperature is 132134C. After 8 hours, 39.5g of water is recovered and the heating is discontinued. After washing with water, and evaporation of the benzene, there is obtained 658 g of a composition of unsaturated ester. Into a reaction vessel of a capacity or 500 ml, equipped with a stirring system, there are introduced 200 g of this composition of unsaturated ester, 24 g of sulfur and 2 g of zinc oxide. The mixture is heated and stirred under a nitrogen atmosphere for 7 hours at 160C and then for 3 hours at 185C. After filtration, there is obtained 22] g of additive VII having the following characteristics:

: 108 cSt 9C 9.9 by weight EXAMPLE 8 According to the same procedure as in Example 7, the reaction is conducted with 570 g (2 acid equivalents) of fatty acids of Tall Oil, 156 g 1.5 mole) of neopentyl glycol and 73 g (0.5 mole) of adipic acid. After evaporation of the benzene and washing with water, 738 g of a composition of unsaturated ester is recovered. The mixture of 160 g of said composition of unsaturated ester with 40 g of 2-ethylhexyl maleate are reacted with 20 g of elemental sulfur according to the same procedure as in example 7. After filtration, there is obtained 219 g of additive VIII, having the following characteristics:

: 62 cSt 12C 8.3 by weight EXAMPLE 9 According to the same procedure as in example 7, the reaction is conducted with 570 g (2 acid equivalents) of fatty acids of Tall Oil, 74.4 g (1.2 mole) of ethyleneglycol and 29.2 g (0.2 mole) of adipic acid. After evaporation of the benzene and washing with water, 621 g of a composition of unsaturated ester is obtained.

A mixture of 140 g of said composition of unsaturated ester with 60g of the ester of isononanol with the fatty acids of Tall Oil is reacted with 29 g of elemental sulfur according to the same procedure as in example 7. After filtration, there is obtained 224 g of additive IX having the following characteristics:

Viscosity at 989C 47 cSt Pour point 10C Sulfur content 11.6 by weight EXAMPLE 10 According to the same procedure as in example 7, the reaction is conducted with 570 g (2 acid equivalents) of fatty acids of Tall Oil, 114.5 g (1.1 mole) of neopentylglycol and 9.8 g (0.1 mole) of maleic anhydride. After evaporation of the benzene and washing with water, 653 g of a composition of unsaturated ester is obtained.

According to the same procedure as in example 7, 200 g of this composition of unsaturated ester is reacted with 25 g of elemental sulfur. After filtration, there is obtained 22g of additive X having the following characteristics:

: 99 cSt 6C 10.1 by weight EXAMPLE 1 1 According to the same procedure as in Example 7, the reaction is conducted with 570 g (2 acid equivalents) of fatty acids of Tall Oil, g 1.2 mole) of neopentyl glycol and 19.6 g (0.2 mole) of maleic anhydride. 43.2 g of water is recovered. After washing with water and evaporation of the solvent, 675 g of a composition of unsaturated ester is obtained.

According to the same procedure as in Example 7, a mixture of g of said composition of unsaturated ester with 60g of 2-ethyl hexyl oleate are reacted with 38 g of elemental sulfur. After filtration, there is obtained 233 g of additive XI, having the following characteristics:

Viscosity at 989C Pour point Sulfur content In order to estimate the anti-wear and extreme pressure properties of the additives prepared as described in examples 1 to 1 1, each of them is dissolved, at a concentration of 3 by weight, in a base oil (A) and the properties of the resulting composition are estimated on testing machines.

The base oil (A) consists of a mixture, by equal amounts, of a mineral oil Neutral and a mineral oil 400 Neutral. The testing machines used are, on the one hand, the so-called 4 ball machine (Extreme pressure tester) for determining the load-wear index (L.W.I.), according to the standard ASTM D 2783-71 and, on the other hand, the FZG machine for determining the damage level (i.e., the seizing level estimated in the range of l to 12), and the specific wear (i.e., the average slope of the wear curve before seizing, expressed in mg/hp.hour, according to the German standard DIN 51 354 of January 1970 with weighing of the gears). The results are given in table I hereunder. By way of comparison, the results obtained when testing the base oil (A) alone and the same base oil containing given in Table I.

TABLE I l..W .l. Dam- Specific age Formulation (kg) level wear mg/hp. hour Base oil (A) 20.1 6 0.320 (A) 3% b.w. of sulfurized spermaceti 011 45.2 10 0.142 (A) 3% b.w. of additive 1 62.4 12 0.112 (A) 3% b.w. of additive II 57.4 11 0.120 (A) 3% b.w. of additive Ill 48.0 10 0.134 (A) 3% b.w. of additive W 60.3 12 0.116 (A) 3% b.w. of additive V 56.2 11 0.123 (A) 3% b.w. of additive V! 54.0 1 1 0.119 (A) 3% b.w. of additive VII 61.1 12 0.114 (A) 3% b.w. of additive VIII 59.0 12 0.115 (A) 3% b.w. of additive IX 61.3 12 0.112 (A) 3% b.w. of additive X 61.0 12 0.112 (A) 3% b.w. of additive X1 62.0 12 0.095

What we claim is:

1. A sulfurized composition suitable for use as an additive for lubricants, resulting from sulfurization of a composition comprising of from 10 to 100% by moles of at least one unsaturated complex ester of the general formula:

and from 0 to 90% by moles of at least one unsaturated ester of the general formula:

0 R. c -o R.-o c iz, (2

in which the radicals R contain to 23 carbon atoms and are monovalent aliphatic hydrocarbon remainders of monocarboxylic acids comprising at least one acid having an ethylenic aliphatic chain, radicals R contain 2 to 6 carbon atoms and are selected from the divalent aliphatic hydrocarbon remainders of diols and the divalent groups of the formula R O m R wherein R is a divalent saturated aliphatic hydrocarbon radical and m is about 1 or 2 and the radical R contains l to 20 carbon atoms and is a divalent aliphatic hydrocarbon remainder of dicarboxylic acid, said sulfurization being conducted by heating the ester composition in the presence of sufficient elemental sulfur to obtain in said composition about 6-15% by weight of reacted sulfur.

2. A composition according to claim 1, in which the radicals R are derived from a mixture of monocarboxylic acids which contain at least one acid having a monoethylenic aliphatic chain and at least one acid selected from the acids with a saturated aliphatic chain and the acids whose aliphatic chain has more than one ethylenic unsaturation.

3. A composition according to claim 2, in which the radicals R contain from 15 to 17 carbon atoms.

4. A composition according to claim 2, in which the radicals R, are derived from a mixture of fatty acids issued from the distillation of Tall Oil.

5. A composition according to claim 1, in which the radicals R, are divalent groups of the formula {R 0),. R wherein R is a divalent saturated aliphatic radical having from 2 to 3 carbon atoms and the integer m is 1 or 2.

6. A composition according to claim 1, in which the sulfur content is from 6 to 12 by weight.

7. A composition according to claim 1 whereinthe degree of unsaturation of the esters prior to sulfurization is about 0.20 to about 0.60 ethylenic bonds per grams.

8. A composition according to claim 1 wherein the unsaturated ester complex ester comprises less than 100% of ester (1).

9. A composition according to claim 6 wherein the unsaturated ester complex ester comprises less than 100% of ester (1), and wherein the sulfurization is conducted in the presence of zinc oxide.

10. A composition as defined by claim 1 further reacted with phosphorous sesquisulfide.

11. A composition according to claim 1, wherein the ester composition prior to sulfurization further contains about 10-40% by weight of an ester of a monohydric aliphatic alcohol having from 1 to 13 carbon atoms with a monocarboxylic acid having from 11 to 23 carbon atoms.

12. A composition according to claim 1, wherein the sulfurization is conducted at l45200C.

13. A composition according to claim 12 wherein the unsaturated ester complex ester comprises less than 100% of ester (1), and wherein the sulfurization is conducted in the presence of zinc oxide.

14. A composition according to claim 5, in which the radicals R are derived from a mixture of fatty acids issued from the distillation of Tall Oil.

15. A sulfurized composition according to claim 1, wherein the composition prior to sulfurization is produced by the total esterification of at least one diol of the formula HO R OH by a mixture of at least one monocarboxylic acid of the formula R CO OH and at least one dicarboxylic acid of the formula HO CO R CO 01-1, the proportion of dicarboxylic acid being 0.05 to 0.5 mole per mole of monocarboxylic acid.

16. A sulfurized composition suitable for use as an additive for lubricants resulting from sulfurization of a composition produced by the total esterification of at least one diol of the formula HO R Ol-l by a mixture of at least one monocarboxylic acid of the formula R CO OH and at least one dicarboxylic acid of the formula HO CO R CO OH, the proportion of dicarboxylic acid being 0.05 to 0.5 mole per mole of monocarboxylic acid in which the radicals R contain 15 to 17 carbon atoms and are monovalent aliphatic hydrocarbon remainders of monocarboxylic acids comprising at least one acid having an ethylenic aliphatic chain, radicals R contain 2 to 6 carbon atoms and are selected from the divalent aliphatic hydrocarbon remainders of diols and the divalent groups of the formula R O m R wherein R is a divalent saturated aliphatic ydrocarbon radical and m is about 1 or 2 and the radical R contains 4 to 6 carbon atoms and is a divalent aliphatic hydrocarbon remainder of dicarboxylic acid, said sulfurization being conducted by heating the ester composition in the presence of sufficient elemental sulfur to obtain in said composition about 615% by weight of reacted sulfur.

17. A composition according to claim 16, wherein the sulfurization is conducted in the presence of zinc oxide.

bon atoms.

19. A composition according to claim 1, wherein the sulfurization is conducted in the presence of zinc oxide. 

1. A SULFURIZED COMPOSITION SUITABLE FOR USE AS AN ADDITIVE FOR LUBRICANTS, RESULTING FROM SULFURIZATON OF A COMPOSITION COMPRISING OF FROM 10 TO 100% BY MOLES OF AT LEAST ONE UNSATURATED COMPLEX ESTER OF THE GENERAL FORMULA:
 2. A composition according to claim 1, in which the radicals R1 are derived from a mixture of monocarboxylic acids which contain at least one acid having a monoethylenic aliphatic chain and at least one acid selected from the acids with a saturated aliphatic chain and the acids whose aliphatic chain has more than one ethylenic unsaturation.
 3. A composition according to claim 2, in which the radicals R1 contain from 15 to 17 carbon atoms.
 4. A composition according to claim 2, in which the radicals R1 are derived from a mixture of fatty acids issued from the distillation of Tall Oil.
 5. A composition according to claim 1, in which the radicals R2 are divalent groups of the formula -R - O-m R - wherein R is a divalent saturated aliphatic radical having from 2 to 3 carbon atoms and the integer m is 1 or
 2. 6. A composition according to claim 1, in which the sulfur content is from 6 to 12 % by weight.
 7. A composition according to claim 1 wherein the degree of unsaturation of the esters prior to sulfurization is about 0.20 to about 0.60 ethylenic bonds per 100 grams.
 8. A composition according to claim 1 wherein the unsaturated ester complex ester comprises less than 100% of ester (1).
 9. A composition according to claim 6 wherein the unsaturated ester complex ester comprises less than 100% of ester (1), and wherein the sulfurization is conducted in the presence of zinc oxide.
 10. A composition as defined by claim 1 further reacted with phosphorous sesquisulfide.
 11. A composition according to claim 1, wherein the ester composition prior to sulfurization further contains about 10-40% by weight of an ester of a monohydric aliphatic alcohol having from 1 to 13 carbon atoms with a monocarboxylic acid having from 11 to 23 carbon atoms.
 12. A composition according to claim 1, wherein the sulfurization is conducted at 145*-200*C.
 13. A composition according to claim 12 wherein the unsaturated ester complex ester comprises less than 100% of ester (1), and wherein the sulfurization is conducted in the presence of zinc oxide.
 14. A composition according to claim 5, in which the radicals R1 are derived from a mixture of fatty acids issued from the distillation of Tall Oil.
 15. A sulfurized composition according to claim 1, wherein the composition prior to sulfurization is produced by the total esterification of at least one diol of the formula HO - R2 - OH by a mixture of at least one monocarboxylic acid of the formula R1 - CO - OH and at least one dicarboxylic acid of the formula HO - CO - R3 - CO - OH, the proportion of dicarboxylic acid being 0.05 to 0.5 mole per mole of monocarboxylic acid.
 16. A sulfurized composition suitable for use as an additive for lubricants resulting from sulfurization of a composition produced by the total esterification of at least one diol of the formula HO - R2 - OH by a mixture of at least one monocarboxylic acid of the formula R1 - CO - OH and at least one dicarboxylic acid of the formula HO - CO - R3 - CO - OH, the proportion of dicarboxylic acid being 0.05 to 0.5 mole per mole of monocarboxylic acid in which the radicals R1 contain 15 to 17 carbon atoms and are monovalent aliphatic hydrocarbon remainders of monocarboxylic acids comprising at least one acid having an ethylenic aliphatic chain, radicals R2 contain 2 to 6 carbon atoms and are selected from the divalent aliphatic hydrocarbon remainders of diols and the divalent groups of the formula - R -O - m - R -, wherein R is a divalent saturated aliphatic hydrocarbon radical and m is about 1 or 2 and the radical R3 contains 4 to 6 carbon atoms and is a divalent aliphatic hydrocarbon remainder of dicarboxylic acid, said sulfurization being conducted by heating the ester composition in the presence of sufficient elemental sulfur to obtain in said composition about 6-15% by weight of reacted sulfur.
 17. A composition according to claim 16, wherein the sulfurization is conducted in the presence of zinc oxide.
 18. A composition according to claim 17, wherein the ester composition prior to sulfurization further contains about 10-40% by weight of an ester of a monohydric aliphatic alcohol having from 1 to 13 carbon atoms with a monocarboxylic acid having from 11 to 23 carbon atoms.
 19. A composition according to claim 1, wherein the sulfurization is conducted in the presence of zinc oxide. 